Results of recent studies strongly suggest that bilateral uncoordinated gait and marked gait asymmetry are associated with FOG. Moreover, it has recently been hypothesized that this may lead to a degree of asymmetric motor function, and that FOG in parkinsonian patients is triggered by a breakdown in the bilateral co-ordination underlying the normal timing of gait. Aim of the study was to evaluate how the modulation of asymmetry through physical therapy might improve gait and FOG.